The present invention relates to improvements in quick-action miniature clamps for securely holding workpieces and the like, and, in one particular aspect, to novel and advantageous orbital-motion clamps which lend themselves to low-cost fabrication and to ready installation and rapid low-profile clamping of workpieces which are to undergo machining.
Numerous forms and types of clamps have long been known in the art, including those which rely upon such mechanisms as screw threads, wedges and/or cams to develop motions which will press or hold items in place while they are being processed in some manner. In connection with machine-tool operations, for example, there are many different powered tools which are designed to operate in diverse ways upon workpieces of various shapes and bulks; economy often dictates that a substantial number of such workpieces be collected closely together and machined in group fashion, particularly if they are relatively small, and that of course suggests that whatever strong clamping is used to hold them reliably should nevertheless not obstruct or unduly retard machining operations, and, also, that it should be possible to both clasp and release the workpieces quickly and easily. A system in which screw-threading serves to force clamp bars against a machined workpiece appears in U.S. Pat. No. 4,526,354, but there the bars must extend over the workpiece and springs are used to facilitate release. Wedging action is relied upon to exert holding pressures in a machine tool bed in U.S. Pat. No. 4,208,045; however, that arrangement involves complexities, bulk and adjustment difficulties which do not favor its use to hold numerous small parts. In respect of camming-type clamps, U.S. Pat. No. 2,788,688 employs a lever-operated cam in a bench vise, and U.S. Pat. No. 2,430,613 utilizes cams in the nature of eccentric wedge blocks which should be screw-locked in place, and U.S. Pat. Nos. 4,157,819 and 4,477,064 respectively show a pair of oppositely-spiralling clamps and eccentrically-pivoted discs, both relying upon wedging actions to oppose unintended loosenings.